FIG. 1 is a block diagram of a remote animal training system, in accordance with a prior art device. More specifically, FIG. 1 is an edited copy of FIG. 2A, from U.S. Pat. No. 5,666,908, disclosing a receiver unit 130 having an antenna 212. The antenna 212 receives an RF signal containing a code representing one of a number of possible levels of stimulation selectable on a remote transmitter (not shown). The RF signal is detected and demodulated by receiver 210 and a “detector” or demodulator 220. The demodulated code is serially input to microprocessor 230 and stored in memory 231 thereof. Microprocessor 230 executes a program to produce output pulses at node 236. The pulse widths of such output pulses (described in the '908 patent and incorporated herein by reference) correspond precisely to one of the possible stimulus levels represented by the stored code. The width of each pulse determines how long the transformer primary winding switch transistor 260 is turned on in response to each output pulse and, thereby, determines the peak-to-peak magnitude of the resulting pulse produced between electrodes 286 and 288 when transistor 260 is turned off at the end of the pulse. The greater the pulse width, the more energy is stored in the core material of the transformer, and the higher the peak-to-peak Flyback or stimulus voltage is between electrodes 286 and 288 immediately after transistor 260 is turned off at the end of each pulse.
To properly train an animal, the trainer must carefully manage the intensity of stimulus being provided to the animal. Inconsistent stimulus levels received by the animal often cause confusion to the animal, which interferes with the training process. A basic requirement of a remote training device of the general type including stimulus intensity controllable by a remote transmitter is that each remotely selected intensity level must reliably and consistently apply the same electrical stimulus level to the animal being trained. If this requirement is not met, the trainer will be unable to control the consistency of stimulus levels.
A shortcoming of most prior art remote training systems such as described in U.S. Pat. No. 5,666,908 having remotely selectable control of the amplitude of the stimulus signal between the skin-contacting electrodes is that for the lower values of the intensity settings, the open circuit and/or the “loaded” electrode voltages applied between the contacting electrodes may not be high enough to cause effective electrical contact of the electrodes with the animals' skin. Thus, the animal may not feel and therefore may not respond to the intended stimulus for lower selected intensity control settings. A trainer observing the lack of response then is likely to increase the selected stimulus level on the remote transmitter until the animal responds. At that point, the stimulus level actually felt by the animal may suddenly be much higher than is justified by its behavior and may cause confusion or fright of the animal, which is counterproductive.
The foregoing problems may be caused by a combination of the dryness of the animals' skin, the tightness of the collar pressing the electrodes against the animals' skin, and various other conditions that cause or contribute to ineffective electrical contact of the electrodes with the animals' skin. The only known reliable way of nevertheless ensuring electrical contact of the electrodes to the animals' skin is to ensure that the open circuit output voltage produced by the secondary winding of the output transformer in the receiver is high enough to arc across any gap or insulative barrier between the electrodes and the animals' skin.
Commonly assigned U.S. Pat. No. 4,802,482, to Gerald J. Gonda and Gregory J. Farkas, issued Feb. 7, 1989, incorporated herein by reference, and commonly assigned U.S. Pat. No. 5,054,428, to Gregory J. Farkas, issued Oct. 8, 1991, also incorporated herein by reference, disclose prior remote animal training systems in which intensity of electrical stimulus is remotely controlled by causing the receiver circuits to produce various stimulus waveforms of constant amplitude and selectable duration and/or frequency. The high open circuit stimulus voltage needed is achieved independently of the intensity level selected. The devices disclosed in these patents provide reliable electrical contact of the electrodes to the skin of the animal being trained by providing sufficiently high open circuit voltages to ensure that even low levels of stimulation produced by controlling the output pulse widths and repetition rates are reliably felt by the animal. However, it has been discovered that even though the circuitry disclosed in the foregoing patents is capable of providing the stimulus voltage with a very wide range of selectable pulse widths and pulse frequencies, the physiology of the dogs being trained is such that the effective range of remotely selectable stimulus that can be achieved by adjusting only the pulse widths and repetition rates of the electrode pulses is much less than is desirable for a wide range of training conditions.
Therefore, it has been necessary for professional trainers and others to either manually swap pluggable intensity-level-setting resistors or manually swap resistive contact electrodes (e.g. of the type described in commonly assigned U.S. Pat. No. 5,471,954, issued Dec. 5, 1995) to provide the needed range of remotely controllable stimulus intensity.
Because of the lack of a wide range of nearly immediately selectable stimulus levels in the prior art remote training devices, professional trainers have had to plan particular training sessions so as to include only activities and circumstances likely to cause dog behaviors which would require stimulus levels within the range determined by the pluggable intensity-level-setting resistors and/or the resistive electrodes on the collar mounted receiver unit. Then, if unexpected behavior or unexpected circumstances occurred during the training session, the trainer often was not able to immediately select an effective stimulus level. In such a case, an opportunity for effective training was lost, and the training process may have been set back as a result of inconsistent and/or inappropriate stimulus.
It would be very desirable to be able to provide remotely controlled stimulus levels that can be promptly changed to any desired level within a very broad range so that a trainer can immediately provide stimulus levels appropriate to any dog behavior likely to occur in any environmental circumstance likely to occur during any training session.
Thus, there is an unmet need for an improved remote training device that reliably provides a very wide range of remotely adjustable, consistent intensity levels under a wide variety of different training conditions, with no need to manually modify or manually interchange intensity-setting components on the receiver unit. There also is an unmet need for a remote training device that (1) provides maximum selectability of the intensity of stimulus applied to the animal, and (2) also achieves very reliable, repeatable electrical contact of the electrodes with the animals' skin over the entire desired range of selectable stimulus intensity settings.
The receiver circuitry of some prior collar-mounted receivers for remote animal training systems has driven the output transformer into saturation. This has resulted in very non-linear, unpredictable amplitudes of the stimulus pulses produced by the secondary winding of the transformer.